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From the Genome to 
    the Proteome

The Next Step: 
    Functional Genomics

Human Genome  
    Project FAQ
   ข้อสงสัยที่ถามกันบ่อย

 Benefits and
    Implications of 
    Genome Research
What's a genome?   
    Why is it important?

Stem Cells: A Primer
 ความรู้เบื้องต้นเกี่ยวกับเซลแม่
 แบบ ต้นกำเนิดร่างกายมนุษย์

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   ข้อมูลเพิ่มเติมเกี่ยวกับเซลต้น
   กำเนิดหรือเซลแม่แบบ

   Stem Cells: A Primer

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    Chromosomes

ออโตโซม
    autosomes
โครโมโซมเพศ
   Sex chromosomes

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    เซลต้นแบบมาใช้ในการรักษา
    ทางการแพทย์

    Using cloned human 
    embryos for research

Lysosomal Storage 
   Disorders
(LSD)
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   คู่ที่ 5 

   Cri du chat syndrome




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 From the Genome to the Proteome

From the Genome to the Proteome
 
Cells are the fundamental working units of every living system. All the instructions needed to direct their activities are contained within the chemical DNA (deoxyribonucleic acid). 

The genome is an organism's complete set of DNA. Genomes vary widely in size: the smallest known genome for a free-living organism (a bacterium) contains about 600,000 DNA base pairs, while human and mouse genomes have some 3 billion. Except for mature red blood cells, all human cells contain a complete genome. DNA from all organisms is made up of the same chemical and physical components. The DNA sequence is the particular side-by-side arrangement of bases along the DNA strand (e.g., ATTCCGGA). This order spells out the exact instructions required to create a particular organism with its own unique traits. 

In humans, as in other higher organisms, a DNA molecule consists of two strands that wrap around each other to resemble a twisted ladder whose sides, made of sugar and phosphate molecules, are connected by rungs of nitrogen-containing chemicals called bases. Each strand is a linear arrangement of repeating similar units called nucleotides, which are each composed of one sugar, one phosphate, and a nitrogenous base. Four different bases are present in DNA: adenine (A), thymine (T), cytosine (C), and guanine (G).  The particular order of the bases arranged along the sugar-phosphate backbone is called the DNA sequence; the sequence specifies the exact genetic instructions required to create a particular organism with its own unique traits.

The two DNA strands are held together by weak bonds between the bases on each strand, forming base pairs (bp). Genome size is usually stated as the total number of base pairs; the human genome contains roughly 3 billion bp.

If unwound and tied together, the strands of human DNA would stretch more than 5 feet but would be only 50 trillionths of an inch wide. For each organism, the components of these slender threads encode all the information necessary for building and maintaining life, from simple bacteria to remarkably complex human beings. Understanding how DNA performs this function requires some knowledge of its structure and organization.
Each time a cell divides into two daughter cells, its full genome is duplicated; for humans and other complex organisms, this duplication occurs in the nucleus. During cell division the DNA molecule unwinds and the weak bonds between the base pairs break, allowing the strands to separate. Each strand directs the synthesis of a complementary new strand, with free nucleotides matching up with their complementary bases on each of the separated strands. Strict base-pairing rules are adhered to; adenine will pair only with thymine (an A-T pair) and cytosine with guanine (a C-G pair). Each daughter cell receives one old and one new DNA strand. The cells' adherence to these base-pairing rules ensures that the new strand is an exact copy of the old one. This minimizes the incidence of errors (mutations) that may greatly affect the resulting organism or its offspring. 
DNA in the human genome is arranged into 24 distinct chromosomes--physically separate molecules that range in length from about 50 million to 250 million base pairs. All genes are arranged linearly along the chromosomes. The nucleus of most human cells contains two sets of chromosomes, one set given by each parent. Each set has 23 single chromosomes--22 autosomes and an X or Y sex chromosome. (A normal female will have a pair of X chromosomes; a male will have an X and Y pair.) Chromosomes contain roughly equal parts of protein and DNA; chromosomal DNA contains an average of 150 million bases. DNA molecules are among the largest molecules now known. 

Chromosomes can be seen under a light microscope and, when stained with certain dyes, reveal a pattern of light and dark bands reflecting regional variations in the amounts of A and T vs G and C. Differences in size and banding pattern allow the 24 chromosomes to be distinguished from each other, an analysis called a karyotype. A few types of major chromosomal abnormalities, including missing or extra copies or gross breaks and rejoinings (translocations), can be detected by microscopic examination; Down's syndrome, in which an individual's cells contain a third copy of chromosome 21, is diagnosed by karyotype analysis. 

Most changes in DNA, however, are too subtle to be detected by this technique and require molecular analysis. These subtle DNA abnormalities (mutations) are responsible for many inherited diseases such as cystic fibrosis and sickle cell anemia or may predispose an individual to cancer, major psychiatric illnesses, and other complex diseases. 

Each chromosome contains many genes, the basic physical and functional units of heredity. Genes are specific sequences of bases that encode instructions on how to make proteins, the molecules that perform most life functions and even make up the majority of cellular structures. Genes comprise only about 2% of the human genome; the remainder consists of noncoding regions, whose functions may include providing chromosomal structural integrity and regulating where, when, and in what quantity proteins are made. The human genome is estimated to contain 30,000 to 40,000 genes.

Human genes vary widely in length, often extending over thousands of bases, but only about 10% of the genome is known to include the protein-coding sequences (exons) of genes. Interspersed with many genes are intron sequences, which have no coding function. The balance of the genome is thought to consist of other noncoding regions (such as control sequences and intergenic regions), whose functions are obscure.
 
Although genes get a lot of attention, it's the proteins that perform most life functions. Proteins are large, complex molecules made up of smaller subunits called amino acids. Twenty different kinds of amino acids are usually found in proteins. Within the gene, each specific sequence of three DNA bases (codons) directs the cells' protein-synthesizing machinery to add specific amino acids. For example, the base sequence ATG codes for the amino acid methionine. Since 3 bases code for 1 amino acid, the protein coded by an average-sized gene (3000 bp) will contain 1000 amino acids. The genetic code is thus a series of codons that specify which amino acids are required to make up specific proteins. Chemical properties that distinguish the 20 different amino acids cause the protein chains to fold up into specific three-dimensional structures that define their particular functions in the cell. 
The constellation of all proteins in a cell is called its proteome. Unlike the relatively unchanging genome, the dynamic proteome changes from moment to moment in response to tens of thousands of intra- and extracellular environmental signals. A protein's chemistry and behavior is specified by the gene sequence and by the number and identities of other proteins made in the same cell at the same time and with which it associates and reacts. Studies to explore protein structure and their activities, known as proteomics, will be the focus of much research for decades to come and will help elucidate the molecular basis of health and disease. 

The protein-coding instructions from the genes are transmitted indirectly through messenger ribonucleic acid (mRNA), a transient intermediary molecule similar to a single strand of DNA. For the information within a gene to be expressed, a complementary RNA strand is produced (a process called transcription) from the DNA template in the nucleus. This mRNA is moved from the nucleus to the cellular cytoplasm, where it serves as the template for protein synthesis. The cells' protein-synthesizing machinery then translates the codons into a string of amino acids that will constitute the protein molecule for which it codes. In the laboratory, the mRNA molecule can be isolated and used as a template to synthesize a complementary DNA (cDNA) strand, which can then be used to locate the corresponding genes on a chromosome map. 

 

 


What We've Learned So Far...Achievement of a Draft Sequence

In June of 2000, HGP leaders, Craig Venter of the private company Celera Genomics, and President Clinton announced the completion of a "working draft" DNA sequence of the human genome.

In February 2001, HGP and Celera Genomics scientists published the long-awaited details of the working-draft DNA sequence achieved less than a year before. Although the draft is filled with mysteries, the first panoramic view of the human genetic landscape has revealed a wealth of information and some early surprises. Papers describing research observations in the journals Nature (Feb. 15, 2001) and Science (Feb. 16, 2001) are freely accessible via the Web.

Although clearly not a Holy Grail or Rosetta Stone for deciphering all of biology two early metaphors commonly used to describe the coveted prize the sequence is a magnificent and unprecedented resource that will serve as a basis for research and discovery throughout this century and beyond. It will have diverse practical applications and a profound impact upon how we view ourselves and our place in the tapestry of life around us.

One insight already gleaned from the sequence is that, even on the molecular level, we are more than the sum of our 35,000 or so genes. Surprisingly, this newly estimated number of genes is only one-third as great as previously thought and is only twice as many as those of a tiny transparent worm, although the numbers may be revised as more computational and experimental analyses are performed. At once humbled and intrigued by this finding, scientists suggest that the genetic key to human complexity lies not in the number of genes but in how gene parts are used to build different products in a process called alternative splicing. Other sources of added complexity are the thousands of post-translational chemical modifications made to proteins and the repertoire of regulatory mechanisms controlling these processes.

The draft encompasses 90% of the human genome's euchromatic portion, which contains the most genes. In constructing the working draft, the 16 genome sequencing centers produced over 22.1 billion bases of raw sequence data, comprising overlapping fragments totaling 3.9 billion bases and providing sevenfold coverage (sequenced seven times) of the human genome. Over 30% is high-quality, finished sequence, with eight- to tenfold coverage, 99.99% accuracy, and few gaps. All data are freely available via the Web.

The entire working draft will be finished to high quality by 2003. Coincidentally, that year also will be the 50th anniversary of Watson and Crick's publication of DNA structure that launched the era of molecular genetics (www.nature.com/genomics/human/watson-crick). Much will remain to be deciphered even then. Some highlights from Nature, Science, and The Wellcome Trust follow.

What Does the Draft Human Genome Sequence Tell Us?

By the Numbers

  • The human genome contains 3164.7 million chemical nucleotide bases (A, C, T, and G).
  • The average gene consists of 3000 bases, but sizes vary greatly, with the largest known human gene being dystrophin at 2.4 million bases.
  • The total number of genes is estimated at 30,000 to 35,000 much lower than previous estimates of 80,000 to 140,000 that had been based on extrapolations from gene-rich areas as opposed to a composite of gene-rich and gene-poor areas.
  • Almost all (99.9%) nucleotide bases are exactly the same in all people.
  • The functions are unknown for over 50% of discovered genes.
The Wheat from the Chaff
  • Less than 2% of the genome codes for proteins.
  • Repeated sequences that do not code for proteins ("junk DNA") make up at least 50% of the human genome.
  • Repetitive sequences are thought to have no direct functions, but they shed light on chromosome structure and dynamics. Over time, these repeats reshape the genome by rearranging it, creating entirely new genes, and modifying and reshuffling existing genes.
  • During the past 50 million years, a dramatic decrease seems to have occurred in the rate of accumulation of repeats in the human genome.
How It's Arranged
  • The human genome's gene-dense "urban centers" are predominantly composed of the DNA building blocks G and C.
  • In contrast, the gene-poor "deserts" are rich in the DNA building blocks A and T. GC- and AT-rich regions usually can be seen through a microscope as light and dark bands on chromosomes.
  • Genes appear to be concentrated in random areas along the genome, with vast expanses of noncoding DNA between.
  • Stretches of up to 30,000 C and G bases repeating over and over often occur adjacent to gene-rich areas, forming a barrier between the genes and the "junk DNA." These CpG islands are believed to help regulate gene activity.
  • Chromosome 1 has the most genes (2968), and the Y chromosome has the fewest (231).
How the Human Compares with Other Organisms
  • Unlike the human's seemingly random distribution of gene-rich areas, many other organisms' genomes are more uniform, with genes evenly spaced throughout.
  • Humans have on average three times as many kinds of proteins as the fly or worm because of mRNA transcript "alternative splicing" and chemical modifications to the proteins. This process can yield different protein products from the same gene.
  • Humans share most of the same protein families with worms, flies, and plants, but the number of gene family members has expanded in humans, especially in proteins involved in development and immunity.
  • The human genome has a much greater portion (50%) of repeat sequences than the mustard weed (11%), the worm (7%), and the fly (3%).
  • Although humans appear to have stopped accumulating repeated DNA over 50 million years ago, there seems to be no such decline in rodents. This may account for some of the fundamental differences between hominids and rodents, although gene estimates are similar in these species. Scientists have proposed many theories to explain evolutionary contrasts between humans and other organisms, including those of life span, litter sizes, inbreeding, and genetic drift.
Variations and Mutations
  • Scientists have identified about 1.4 million locations where single-base DNA differences (SNPs) occur in humans. This information promises to revolutionize the processes of finding chromosomal locations for disease-associated sequences and tracing human history.
  • The ratio of germline (sperm or egg cell) mutations is 2:1 in males vs females. Researchers point to several reasons for the higher mutation rate in the male germline, including the greater number of cell divisions required for sperm formation than for eggs.
Applications, Future Challenges
Deriving meaningful knowledge from the DNA sequence will define research through the coming decades to inform our understanding of biological systems. This enormous task will require the expertise and creativity of tens of thousands of scientists from varied disciplines in both the public and private sectors worldwide.

The draft sequence already is having an impact on finding genes associated with disease. Over 30 genes have been pinpointed and associated with breast cancer, muscle disease, deafness, and blindness. Additionally, finding the DNA sequences underlying such common diseases as cardiovascular disease, diabetes, arthritis, and cancers is being aided by the human variation maps (SNPs) generated in the HGP in cooperation with the private sector. These genes and SNPs provide focused targets for the development of effective new therapies.

One of the greatest impacts of having the sequence may well be in enabling an entirely new approach to biological research. In the past, researchers studied one or a few genes at a time. With whole-genome sequences and new high-throughput technologies, they can approach questions systematically and on a grand scale. They can study all the genes in a genome, for example, or all the transcripts in a particular tissue or organ or tumor, or how tens of thousands of genes and proteins work together in interconnected networks to orchestrate the chemistry of life. 


 

The Next Step: Functional Genomics

The words of Winston Churchill, spoken in 1942 after 3 years of war, capture well the HGP era: "Now this is not the end. It is not even the beginning of the end. But it is, perhaps, the end of the beginning."

The avalanche of genome data grows daily. The new challenge will be to use this vast reservoir of data to explore how DNA and proteins work with each other and the environment to create complex, dynamic living systems. Systematic studies of function on a grand scale-functional genomics-will be the focus of biological explorations in this century and beyond. These explorations will encompass studies in transcriptomics, proteomics, structural genomics, new experimental methodologies, and comparative genomics.

  • Transcriptomics involves large-scale analysis of messenger RNAs transcribed from active genes to follow when, where, and under what conditions genes are expressed.
  • Studying protein expression and function--or proteomics--can bring researchers closer to what's actually happening in the cell than gene-expression studies. This capability has applications to drug design.
  • Structural genomics initiatives are being launched worldwide to generate the 3-D structures of one or more proteins from each protein family, thus offering clues to function and biological targets for drug design.
  • Experimental methods for understanding the function of DNA sequences and the proteins they encode include knockout studies to inactivate genes in living organisms and monitor any changes that could reveal their functions.
  • Comparative genomics--analyzing DNA sequence patterns of humans and well-studied model organisms side-by-side-has become one of the most powerful strategies for identifying human genes and interpreting their function.

 

Select a Subject
  • Human Genome Project --answers to the who, what, when, why, and how much of the Project
  • Benefits and Implications of Genome Research --information about Project benefits, the ethical, legal, and social issues associated with the project, gene testing, and medicine
  • Genetics --answers to whose genome is being used, what's a genome, how big is a genome, what is model organism research, what is cloning, where can I find out about a particular disease, and other questions

 

 

Human Genome Project


Q. What is the Human Genome Project?

The Human Genome Project (HGP) is an international 13-year effort formally begun in October 1990. The project was planned to last 15 years, but rapid technological advances have accelerated the expected completion date to 2003. Project goals are to discover all the approximate 30,000 to 35,000 human genes (the human genome) and make them accessible for further biological study and to determine the complete sequence of the 3 billion DNA subunits (bases). As part of the HGP, parallel studies are being carried out on selected model organisms such as the bacterium E. coli to help develop the technology and interpret human gene function. The Department of Energy's Human Genome Program and the National Institutes of Health's National Human Genome Research Institute (NHGRI) together make up the U.S. Human Genome Project.

A rough draft of the human genome was completed in June 2000. Efforts are still underway to complete the finished, high-quality sequence.

For more information, see About the Human Genome Project. [01/01]


Q. Who is head of the U.S. Human Genome Project?

The Department of Energy's Human Genome Program is directed by Ari Patrinos, head of the Office of Biological and Environmental Research. Francis Collins directs the National Institutes of Health National Human Genome Research Institute. [01/01]

 


Q. How far along is the project? How many genes have been identified?

In June 2000, scientists completed the first working draft of the human genome. Efforts are still underway to complete a high-quality, "finished" sequence. See the Human Genome Project Progress Web page for an update on all aspects of the Human Genome Project including sequencing, mapping, BAC End sequencing, and ethical, legal, and social issues. See also the Human Genome Project History Web page.[01/01]

 


Q. What are the goals of the Human Genome Project?

See the Human Genome Project Goals Web page for the latest HGP goals (1998-2003). [01/01]

 


Q. What U.S. laboratories and investigators are involved in the Human Genome Project?

Many laboratories around the United States receive funding from either the Department of Energy (DOE) or the National Institutes of Health (NIH), or both, for Human Genome Project research. A list of the major U.S. and international Human Genome Project research sites can be found here.

Other researchers at numerous colleges, universities, and laboratories throughout the United States also receive DOE and NIH funding for human genome research. At any given time, the DOE Human Genome Program funds about 200 separate principal investigators. For DOE-funded projects, see Research in Progress. See a list of NIH-funded projects here.

In addition, many private companies are conducting genome research. For more on this, see the HGP and the Private Sector Fact Sheet. [01/01]

 


Q. What other countries are participating in the HGP?

At least 18 countries have established human genome research programs. Some of the larger programs are in Australia, Brazil, Canada, China, Denmark, European Union, France, Germany, Israel, Italy, Japan, Korea, Mexico, Netherlands, Russia, Sweden, United Kingdom, and the United States. Some developing countries are participating through studies of molecular biology techniques for genome research and studies of organisms that are particularly interesting to their geographical regions. The Human Genome Organisation (HUGO) helps to coordinate international collaboration in the genome project.

A list of the major U.S. and international Human Genome Project research sites can be found here. [01/01]

 


Q. What happens when the genome sequence is completed?

Completing the genome sequence is just the first step. See a list of post-sequencing research challenges on the Sequencing Fact Sheet. [01/01]


Q. The Human Genome Project published papers about the working draft sequence in February 2001. What was learned from this working draft sequence?

See an index of the papers and a list of insights learned from this information. [2001]


Q. About how much have the Department of Energy and the National Institutes of Health spent on the Human Genome Project since it began in 1988?

See the joint DOE-NIH Budget of the Human Genome Project. [08/00]

 


Q. Why is the Department of Energy (DOE) involved in the Human Genome Project?

See the answer on the Department of Energy and the HGP Fact Sheet. [01/01]

 


Q. What DOE investments have improved the Human Genome Project by reducing costs, speeding progress, furthering technology?

See the answer on the Department of Energy and the HGP Fact Sheet. [01/01]


Q. Where can I find details about the Department of Energy's Human Genome Program?

See the answer on the Department of Energy and the HGP Fact Sheet. [01/01]

 


return to subject listing at top of page

 

Benefits and Implications of Genome Research

Q. What are the potential benefits of human genome research?

The project will reap fantastic benefits for humankind, some that we can anticipate and others that will surprise us. Generations of biologists and researchers will be provided with detailed DNA information that will be key to understanding the structure, organization, and function of DNA in chromosomes. Genome maps of other organisms will provide the basis for comparative studies that are often critical to understanding more complex biological systems. Information generated and technologies developed will revolutionize future biological explorations.

For details about the applications of human genome project research, see Potential Benefits of Human Genome Project Research.

Click here to see a poster depicting resources gained from Human Genome Project research. [01/01]

 


Q. What are some of the ethical, legal, and social challenges presented by genetic information, and what is being done to address these issues?

The DOE and NIH genome programs set aside 3% to 5% of their respective total annual budgets for the study of the project's ethical, legal, and social issues (ELSI). For an in-depth look at the ELSI surrounding the project, see Ethical, Legal, and Social Issues (ELSI) of the Human Genome Project. For more on ongoing ELSI research, see our ELSI Research page.[01/01]


Q. What laws exist to protect us from genetic discrimination in insurance and in the workplace?

See the answer on our Privacy and Legislation Web page. [08/00]

 


Q. What is gene patenting? Is DNA patentable? What laws govern gene patenting?

See the answer on our Patenting Web page. [01/01]


Q. What is gene testing? How does it work?

See the answer on our Gene Testing Web page. [01/01]


Q. Does behavior have a biological basis? Are our actions and emotions related to our genetic makeup?

See the answer on our Behavioral Genetics Web page. [01/01]


Q. How can you be identified by your DNA? What are other applications for DNA forensics? If we are 99% alike, won't two people likely have the same DNA makeup?

See the answer on our DNA Forensics page. [01/01]

 


Q. How will the Human Genome Project impact medicine?

See the answer on our Medicine and the New Genetics Web page. [08/00]


Q. Where can I find easy-to-understand information about a specific genetic disease?

See the answer on the Genetic Disease Information Web page.[01/01]


Q. Is gene therapy being used to cure diseases? What is its promise for the future of medicine?

See the answer on our Gene Therapy Web page. [01/01]


Q. What is pharmacogenomics? How will it change my trips to the doctor's office?

See the answer on our Pharmacogenomics Web page. [01/01]


Q. What do genetic counselors do? Why would I need one? How can I become one?

See the answer on our Genetic Counseling Web page. [01/01]

 

 

 


return to subject listing at top of page

 

Genetics

Q. What's a genome? And why is it important?

A genome is all the DNA in an organism, including its genes. Genes carry information for making all the proteins required by all organisms. These proteins determine, among other things, how the organism looks, how well its body metabolizes food or fights infection, and sometimes even how it behaves.

DNA is made up of four similar chemicals (called bases and abbreviated A, T, C, and G) that are repeated millions or billions of times throughout a genome. The human genome, for example, has 3 billion pairs of bases.

The particular order of As, Ts, Cs, and Gs is extremely important. The order underlies all of life's diversity, even dictating whether an organism is human or another species such as yeast, rice, or fruit fly, all of which have their own genomes and are themselves the focus of genome projects. Because all organisms are related through similarities in DNA sequences, insights gained from nonhuman genomes often lead to new knowledge about human biology. [01/01]

 


Q. How big is the human genome?

The human genome is made up of DNA, which has four different chemical building blocks. These are called bases and abbreviated A, T, C, and G. In the human genome, about 3 billion bases are arranged along the chromosomes in a particular order for each unique individual. To get an idea of the size of the human genome present in each of our cells, consider the following analogy: If the DNA sequence of the human genome were compiled in books, the equivalent of 200 volumes the size of a Manhattan telephone book (at 1000 pages each) would be needed to hold it all.

It would take about 9.5 years to read out loud (without stopping) the 3 billion bases in a person's genome sequence. This is calculated on a reading rate of 10 bases per second, equaling 600 bases/minute, 36,000 bases/hour, 864,000 bases/day, 315,360,000 bases/year.

Storing all this information is a great challenge to computer experts known as bioinformatics specialists. One million bases (called a megabase and abbreviated Mb) of DNA sequence data is roughly equivalent to 1 megabyte of computer data storage space. Since the human genome is 3 billion base pairs long, 3 gigabytes of computer data storage space are needed to store the entire genome. This includes nucleotide sequence data only and does not include data annotations and other information that can be associated with sequence data.

As time goes on, more annotations will be entered as a result of laboratory findings, literature searches, data analyses, personal communications, automated data-analysis programs, and auto annotators. These annotations associated with the sequence data will likely dwarf the amount of storage space actually taken up by the initial 3 billion nucleotide sequence. Of course, that's not much of a surprise because the sequence is merely one starting point for much deeper biological understanding!

Contributions to this answer were made by Morey Parang and Richard Mural formerly of Oak Ridge National Laboratory; and Mark Adams formerly of The Institute of Genome Research. [01/01]

 


Q. Whose genome is being sequenced in the public (HGP) and private projects?

See answer on the Facts About Genome Sequencing page. [01/01]

 


Q. Where can I find maps of genes that have been found on different chromosomes?

See the online poster, Human Genome Landmarks: Selected Traits and Disorders Mapped to Chromosomes. This poster provides chromosome-by-chromosome maps of some of the genes that have been mapped to each chromosomes. These maps were generated using the Online Mendelian Inheritance in Man database.

Another good place to get maps is by accessing the Genome Database (GDB), which is the worldwide repository of human genome mapping data. A feature allows users to list genes by chromosome and to print maps (requires PostScript). Go to the main report page.

In conjunction with the October 1998 special genome issue of Science, NCBI released an updated online map of more than 30,000 genes. An older map from the 1996 special genome issue of Science is also available. [01/01]

 


Q. What is DNA sequencing, and how is it done?

See the answer on the Facts About Genome Sequencing page. [01/01]

 


Q. Why is model organism research important? How closely related are mice and humans? Why do we care what diseases mice get?

See the answer on the Functional and Comparative Genomics Fact Sheet. [01/01]

 


Q. What genomes have been sequenced completely?

See the answer on the Functional and Comparative Genomics Fact Sheet. [01/01]

 

 


Q. When is a genome completely sequenced?

See the answer on the Facts About Genome Sequencing page. [01/01]

 

 


Q. What are the comparative genome sizes of humans and other organisms being studied?

See the answer on the Functional and Comparative Genomics Fact Sheet. [01/01]

 


Q. What is jumping DNA?

Nearly half of the human genome is composed of transposable elements or jumping DNA. First recognized in the 1940s by Dr. Barbara McClintock in studies of peculiar inheritance patterns found in the colors of Indian corn, jumping DNA refers to the idea that some stretches of DNA are unstable and "transposable," ie., they can move around—on and between chromosomes.

This theory was confirmed in the 1980s when scientists observed jumping DNA in other genomes. Now scientists believe transposons may be linked to some genetic disorders such as hemophilia, leukemia, and breast cancer. They also believe that transposons may have played critical roles in human evolution.

McClintock received a Nobel prize in 1983 for her discovery—making her one of only two women ever to receive an unshared Nobel prize in science. The other was Marie Curie.

To learn more about McClintock and her research, see

 


Q. What is cloning?

See the answer on the Cloning fact sheet Web page. [01/01]

 


 

This Web site is being continuously updated, and HGMIS appreciates your input. Please send updates, questions, or comments to caseydk@ornl.gov and URL updates or Web questions to martinsa@ornl.gov.

 

 


Last modified: Monday, May 14, 2001



 


 






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